Protective device



H. G. FRENCH.

PROTECTIVE DEVICE.

APPLICATION FILED OCT. 25. 1919.

1,374,727. Patented Apr. 12, 1921.

TIME

I Invehtor: Henry G.Fr-ench,

a I Hrs Attorney UNITED-STATES PATENT OFFICE.

HENRY G. FRENCH,

OF SCHENECTADY, NEW YORK, ASSIGNOR 'IO GENERAL'EEECTRIC.

COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE DEVICE.

Specification of Letters Patent.

Application filed October 25, 1919. Serial No. 333,248.

to provide a relay of the induction type which is operative in responseto a predetermined abnormal condition in a positive and definite manner,which will move positively to contact controlling position and whichembodies other features to be described more in detail hereinafter.

In relays of the induction type in which a rotatable armature iscontrolled by torque and counter-torque elements, it is necessary tocompensate for the increase in eflect of the counter-torque element whenthe armature is actuated by the torque element. Without compensation acurrent just enough to start the armature rotating is insuflicient tocarry the armature positively to complete its path of movement as thearmature will float or move to aposition where the effects of the torqueand counter-torque elements balance. Again the pick-up value of currentfor which the relay is set to operate may not positively start thearmature rotating due to the small increase in torque over the countertorque.

According to my invention, I overcome these disadvantages by providing arelay which has a positive and definite pick-up when the current reachesa predetermined value and which is carried positively and definitely tocomplete its path of movement on that value of current or that drivingtorque sufficient to initially start the armature in rotation.

The novel features which I believe to be characteristic of my inventionwill be definitely indicated in the claims appended hereto while thefeatures of construction and mode of operation will be understood byreference to the following description taken in connection with theaccompanying drawing-in which:

Figure 1 shows, in perspective, a relay embodying my invention; Fig. 2shows, in perspective, a relay embodying a modified form of myinvention, and Fig. 3 is a graphic, illustration of the operatingcharacteristics of my improved relay.

In Fig. 1 the relay of my invention comprises a rotatable armaturemember 1, carried by a shaft 2, which carries a movable contact 3adapted to be moved into and out of engagement with cooperating fiiredcontacts 4 by rotation of the armature, to control an auxiliary circuit.This circuit may operate a trip coil or auxiliary relayto open thecircuit protected by the relay of my 1nvention. The rotatable armature 1is actuated and controlled by a torque-producing element 5 tending todrive or rotate the armature 1 in contact-closing direction, and also bya counter-torque or restraining element 6 producing an opposing orcounter torque tending to rotate the armature 1 in the oppositedirection. Normally the effect of the counter-torque element 6predominates to hold the armature against a stop 7.

The torque-producing element 5 is preferably of the electromagnetic typeconsisting, as shown, of a U-shaped magnetic member 8 upon which ismounted actuating windings 9 connected in series. Upon the pole'tips ofthe magnetic member 8, between which the armature is movable, areshading coils 10 to provide a rotative effect on the armature. Thecounter-torque element 6 is also preferably of the electromagnetic typecomprising a U-shaped magnetic member 11 with actuating windings 12connected in series and in a series circuit with windings 9 of thetorque'element 5. The element 6 is mounted at the opposite side of thearmature 1. from the torque element 5 and is provided with pole tipsbetween which the armature is movable. These pole tips are provided withshading coils 13 which are relatively movable by an adjusting means 14to vary the counter torque as desired.

The counter-torque element 6 is also provided; with a positive pick-updevice consisting of means for automatically short circuiting the fluxacross the pole tips and hence the flux cutting the rotatable 'armasture. This means consistsof leakage poles 15 having an air gapsubstantially greaterthan the gap between the pole tips. This gap isadapted to be bridged to form a shunt path for the flux in response toprethus weaken the For determined conditions and effect ofthecounter-torque element.

Patented Apr. 12, 1921.

enabling the leakage poles to. form a shunt path, provide a plunger 16extending through the lower leakage pole l5 and ad- 5 and 6am connectedin series in the secondary circuit of a transformer 19, the primary orwhich is responsive to the current on the line 20 to be protected. Y

The operation of my relay may be described as follows: normally thecurrent in windings 9 and 12 is such that a small flux is created inmagnetic members 8 and 11, creating opposing torques on the'armature 1.The effect of the counter-torque element 6 normally predominates -tohold the armature against stop 7. When the current in conductor 20reaches a predetermined amount, a proportional current flows throughwindings 9 and 12 increasing the flux in members 8 and 11, and hence thetorque and, counter torque exerted by elements v5 and 6' respectively.The flux in counter-torque element 6' upon this'predetermined value ofcurrent, for which the device is set to operate, is sufiicient tooperate the pick-up device attracting plunger 16 and movingit intoengagement with upper leakage pole 15. The plunger thus bridges theleakage poles and forms a path for I 'the flux in shunt to that acrossthe pole tips of element 6. The result of the attractlon of the plunger16 is to instantly short circuit the flux creating the counter torque onarmature 1 reducing thereby the eflect of the counter-torque element.The driving element 5 thereupon overcomes the counter-torque element andpositively moves the armature 1 to complete its path of movement andbring contacts 3 and 4 into engagement.

\ The engagement of conta cts 3 and 4: functions to enable the circuit20 to be opened. A comparatively light spring 21 is connected to theshaft 2 adapted to be tensioned by the movement of the armature 1 andwhich operates to return'the armature to its initial position whencurrent to the control elements 5 and 6 is interrupted; It is thusapparentithat as soon as the current and hence the flux in thecountertorque element 6 reachesa'predetermilied amount, the pick-updevice automatically operates with a positive action to reduce theeffect of the counter-torque element and enable the torque element 5 toeffectively predominate and move the armature ldefinitely' andpositively intocontact closing position.- All danger of floating isthereby definitely eliminated. The pick-up value and hence the point ofoperation of the relay may be controlled by adjusting the air gapbetween the leakage poles which is accomplished by adjusting theposition ofthe plunger. The armature 1 may be provided with a dragelement, such as a permanent magn'et of well known construction, ifsuchis desired, for giving a time lnterval in the operation of the relay. Ihave not shown such an element in Fig. l for purposes of clearness.

In Fig. 2'I have shown/a modified form of my invention in which therotatable armature member 1 is controlled by a torque element 5 and arestraining or countertorque element. In this case the countertorqueelement 'comprises the spring 21. The movement of armature 1 is delayedby the permanent drag magnet 22. The driving or torque element 5 is ofthe' electromagnetic type having a laminated magnetic member 23 uponwhlch is Wound the. actuating winding 24. controlled from the circuit tobe protected. The armature 1 is rotatable between the polev tips of themagnetic member 23 which are provided with hence the size of the air gapmay be varied by adjusting means 26 to close the magnetic circuit ofmember 25 under any predetermined value of flux or current in winding24. In the arrangement shown', I provide of the magnetic member 23movably positioned and extending through the lower portion 27 of themember. The plunger is surrpunded by a suitable casing 28.

Normally the effect of counter-torque elerment 21 predominates to holdthe armature against the stop 7. Dueto the reluctance of the magneticcurrent of member 23, little flux passes the pole tips and littledriving torque is exerted on the armature 1. Upon increase in current inwinding 24, the flux in member 23 increases until it is sufiicient toattract plunger 25- which moves to close the air gap in the circuit ofmember 23 there by greatly increasing the flux in member 23. Theadjustable plunger 25 serves as a pickup device to greatly increase thetorque exerted by the driving element 5, upon that value of current forwhich'the device is set to operate. When the pick-up value of.current-is reached, the torque exerted by the ,the movable core orplunger 25 as one leg I element 5 positively overcomes the spring orcounter-torque element 21 and moves the armature positively anddefinitely in contact-controlling direction until contacts 3 and 4 arebrought into engagement. Upon the opening of the circuit to beprotected,

pose a thin brass washer may be used on the plunger or an other similarde ice.

In *Fig. 3 have .shown in a graphical manner the time current curve ofthe relay embodying the principles of my invention. Depending on thesetting of the pick-up device, which is noted by the vertical line aa,the relay is held inoperative until the I pick-up value of current 1sreached. ,Upon

the occurrence of the pick-up value of current, the relay is positivelyset into operation and completes its operation definitely and with apositive action. The effect of the pick-up device is, therefore, toeliminate that portion of the time current curve at the left ofthe lineaia, shown in dotted lines, and only that portion ofthe curve isobtained which is shown in a solid line. In this manner the selectiveaction of relays of this type are dependable and the relays are positivein action. I

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. In a relay of the induction type, the. combination with a rotatablearmature, a torque-producing element for moving said armature inresponse to currents above a predetermined amount, an element producinga counter torque normally overcoming said torque element, 'andadjustablemeans responsive to currents of any predetermined amount for varyingthepick-up point of said torque-producing element.

2. A relay device comprising a rotatable armature, contacts controlledthereby, a motor element tending to rotate said armature in"contact-controllin direction, a restraining element normal y renderingsaid motor element inefiective, and means adjustable to operate inresponse to any predetermined value of current for causing said motor.element to'positively overcome said restraining element and carry saidarmature through its complete path of travel into contact-controllingposition.

3.111 an induction relay, the combination with a rotatablearmature,contacts closed'thereby, an electromagnetic element operative inresponse to current above apredetermined amount to turetocontact-closing position, restraining means normally overcoming theeffect of said element, and means adjustable to cause saidelectromagnetic element to overcome said restraining element and movesaid'70 armature into contact-closing position at any predeterminedpoint in the time current curve of said relay.

4. In a relay device, a rotatable armature, thereby, tating saidcontacts in contact-controlling direction, a restraining elementnormally overcoming said torque element, and means the combination withadjustable to operate in'response to abnormal conditions in excess ofany redetermined amount for causin said torque-producing element to quicy and. positively overcome said restraining element and move saidarmature into contact-controlling position.

5. In a relay device of the induction type, the combination with a.rotatable armature. contacts controlled thereby, a motor elementproducing a torque direction to rotate ,the' same in contactcontrollingposition, an electromagnetic element having a magnetic flux adapted toproduce a counter torque on said armature,

means responsive to currents above any predetermined amount for reducingthe flux of said counter-torque element tending to efi'ect said armaturewhereby said motor element predominates to quickly rotate said armatureinto contact-controlling position.

6. In a relay of the induction type, the combination with a rotatablearmature, an electromagnetic element producing a flux tending to rotatesaid armature in one direction, a producing a flux tending to rotatesaid armature in the opposite direction but inefiec= tive until thecurrent exceeds a predetermined amount, means associated with said firstmentioned element operative upon currents above said predeterminedamount to short circuit the flux thereof to permit said armature to movequickly under the influence of said second element.

7. In a relay device, a rotatable armature, contacts controlled thereby,a torque-producing element for rotating said armature intocontact-oontroL ling position, an electromagnetic element producing acounter torque on said armature normally overcoming said torque element,main poles for said counter torque element between which said armatureis movable,

secondary poles for said counter-torque element outside the and meanswhereby the normal path of the flux of said counter-torque element isthrough said main poles but upon the ocrotate said arma- 65 contactscontrolled 75 a torque-producing element for roon said armature in a 90second electromagnetic element 105 the combination with 15 influence ofsaid armature,

currence of current above a predetermined amount the path of said fluxis through said secondary poles. I 1

8. In a relay device, the combination with a rotatable armature,contacts controlled thereby, a torque-producing element for rotatingsaidarmature to contact-controlling position, an electromagnetic elementproducing a counter torque on said armature which normally overcomes theeflect of said torque element, poles for said counter-torque elementbetween which said armature is rotatable, and means adjustable tooperate in response to any predetermined abnormal condition to reducethe flux passing through said main poles whereby the effect of saidtorque element predominates.

9. In a relay device, the combination with a rotatable armature,contacts. controlled thereby, a torque-producing element for rotatingsaid armature to contact-controlling position, an electromagneticelement producing a counter torque on said armature which normallyovercomes the effect of said torque element, main poles for saidcounter-torque element providing a path for the flux through saidarmature, and leakage poles providing a shunt path for said flux withoutaffecting said armature, and means whereby the normal path of said fluxis'through said main poles but upon 'the occurrence of predeterminedabnormal conditions the path of said flux is through said leakage poles.

- 10. In a relay device, the combination with a rotatable armature,contacts controlled thereby, a torque-producing element for, rotatingsaid armature to contact-controlling osition, an electromagnetic elementproducing a counter torque on said armature -which normally overcomestheefi'ect of said torque element, main poles for, said countermy hand this23rd day of October, 1919.

HENRY G. FRENCH.

